1. Field of the invention
The present invention relates to a linear guide apparatus with magnetic distance sensor, and more particularly, to a linear guide apparatus with magnetic distance sensor which can save available space in the linear guide apparatus and thereby minimizing manufacturing cost.
2. Description of the Prior Art
Generally speaking, an industrial linear guide apparatus has low friction characteristic but without having any distance sensing function by magnetic induction. If the location of the slide block on the guide rail is desired to be under control from time to time, a gauge acted by a magnetic sensor or an optical sensor is attached to the apparatus which results in both increasing manufacturing cost and causing inconveniency in operation of the apparatus.
In order to eliminate such shortcomings, there were disclosed some new designs of linear guide apparatus with function of locating the position of the slide block on the linear guide apparatus.
One of such conventional linear guide apparatus with magnetic induction distance sensor is shown in FIG. 4. In this cross sectional drawing it is observed that a magnetic tape 3 is adhered on the upper surface of a rail 1. A chamber 21 for accommodating a magnetic induction element 4 is formed in a part of a slide block 2. Incidentally, the manufacturing cost will be increased and the strength of the slide block's structure will be lowered by forming a chamber 21 therein. In addition, when a concentrated downward load is applied to the slide body 2 causing the upper portion of the slide block 2 to bend down by a bending force, the point contact force (if using rolling balls), or line contact force (if using rolling cylinders) between the slide block 2 and the rail 1 will be loosened by a slight relative displacement of contact portion therebetween. Consequently the strength of the whole linear guide apparatus in transverse direction will be reduced and positioning accuracy for the location of the slide block 2 will also be degraded. In the linear guide apparatus shown in FIG. 4, since the tightening screw bolt for fixing the rail 1 is applied downwardly, the rail 1 has to be made into flatter and wider configuration so as to prevent the magnetic tape 3 from standing in the way of tightening screw bolt hole 11 for fixing the rail 1.
A second type conventional linear guide apparatus with magnetic induction distance sensor is shown in FIG. 5. In this cross sectional drawing it is observed that since the tightening screw bolt for fixing the rail 1 is upwardly installed, therefore the rail 1 is made into normal configuration.
FIGS. 6 and 7 show drawings of a third type conventional linear guide apparatus with magnetic induction distance sensor, FIG. 6 shows its front view while FIG. 7 shows a cross sectional view along line I--I of FIG. 6 respectively. In this conventional linear guide apparatus the magnetic tape 3 is adhered on one of the side surface of the rail 1, the rail 1 is mounted on the base after attaching the tape 3 in order to facilitate the assembly work, but it is inevitable that the tape 3 is prone to be hurt during the assembly work. When the slide block 2 displaces in the transverse direction by a force in the same direction. The variation of the distance between the magnetic tape 3 and the magnetic induction element 4 will be greater than that in the case when the magnetic tape 3 is adhered right on the rail surface therefore affecting sensor's sensitivity. In this linear guide apparatus an induction element chamber 83 with an induction element therein is formed on a base 8 which is mounted on an end case 5. Signal wires 7 are laid in a trough 84 A plurality of through holes 82 are provided for tightening screws 83 to fix the end cap s. An outlet terminal block 81 is for connecting and securing signal wires 7. Slid e block fixing holes 22 are provided for the guide rail 1 and slide block 2. A wiper 9 is attached to the end cap 5 and oil nipple 91 supplies oil to the device.